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Visar resultat 1 - 5 av 29 avhandlingar som matchar ovanstående sökkriterier.

  1. 1. Massive MIMO From a Terminal Perspective

    Författare :Erik L Bengtsson; Institutionen för elektro- och informationsteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Massive MIMO; mm-wave; terminal antenna; channel sounding; Propagation Channel; sub 6 GHz;

    Sammanfattning : This thesis focuses on the terminal aspects of massive MIMO systems. Based on the degree of freedom a terminal have in a MaMi, different antenna configurations, transceiver topologies with associated transmission schemes, and the underlying algorithms are researched. LÄS MER

  3. 2. Planar Quasiparticle Mixer Structures for Millimeter and Sub-Millimeter Wave Receivers

    Författare :Anders Skalare; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; SIS receiver; dipole array antenna; slot substrate mode loss; millimeter wave regime; planar antennas; sub-millimeter wave regime; superconducting mixers; slot radiation; slot lines; slot wavelengths; Voltage Matching Method;

    Sammanfattning : The paper covers various aspects of integrating planar antennas with superconducting mixers in the millimeter and sub-millimeter wave regime. The construction of an 80-100 GHz tapered slot antenna and SIS mixer chip with a minimum double side band noise temperature of 240 K is described. LÄS MER

  4. 3. Microwave Radiometric Observations of the Middle Atmosphere: Simulations and Inversions

    Författare :Patrick Eriksson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; atmospheric radiative transfer; middle atmosphere; sub-mm; data inversion; profile retrieval; microwaves; limb sounding; ozone; remote sensing;

    Sammanfattning : Two well-known examples of global environmental problems are the ozone depletion and the enhanced greenhouse effect. The importance and the complexity of these questions generate a demand for improved atmospheric observations, and microwave radiometry is an approach which is increasingly important for measurements of the middle atmosphere (10-100 km). LÄS MER

  5. 4. Low Noise SIS Mixers and Cryogenic Amplifiers for Sub-Millimeter Astronomy

    Författare :Christophe Risacher; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : This PhD thesis presents the work that was done developing radioastronomy instrumentation. The first part of this work deals with 2-stage low-noise cryogenic amplifiers using commercial GaAs HEMT transistors for frequency bnads: 3.4-4.6 GHz, 4-8 GHz and 8-9 GHz. LÄS MER

  7. 5. Nonlinear optics in KTiOPO4 for spectral management of ultra-short pulses in the near- and mid-IR

    Författare :Anne-Lise Viotti; Valdas Pasiskevicius; Fredrik Laurell; Paulina Kuo; KTH; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nonlinear optics; Ferroelectrics; Fysik; Physics;

    Sammanfattning : This thesis explores the possibilities of controlling nonlinear optical interactions in ferroelectric materials for bandwidth tailoring of ultrashort pulses in the pico- and femto-second range. The control is achieved through quasi-phase matching, which is based on alternating the material’s spontaneous polarization into different domains. LÄS MER